From a9e242ca43b13e5a5d176f97dfd2481c339934b7 Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Thu, 14 Apr 2016 15:33:45 -0400 Subject: [PATCH] ip6gretap: Fix MTU to allow for Ethernet header When we were creating an ip6gretap interface the MTU was about 6 bytes short of what was needed. It turns out we were not taking the Ethernet header into account and as a result we were eating into the 8 bytes reserved for the encap limit. Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller --- net/ipv6/ip6_gre.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 4e636e60a360..2be66e7b4a78 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -987,6 +987,8 @@ static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu) dev->mtu = rt->dst.dev->mtu - addend; if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT)) dev->mtu -= 8; + if (dev->type == ARPHRD_ETHER) + dev->mtu -= ETH_HLEN; if (dev->mtu < IPV6_MIN_MTU) dev->mtu = IPV6_MIN_MTU; -- 2.34.1